1. Field of the Invention:
This invention relates in general to earth boring bits, and in particular to a replaceable tungsten carbide nozzle for use in earth boring bits.
2. Description of the Prior Art:
An earth boring bit of the type concerned herein has a body with a threaded pin on its upper end for connection to a string of drill pipe extending to the surface. The bit has a cutting face on its lower end, which is an integral part of the body. Polycrystalline diamond (PDC) disks are mounted on the face. Normally there are several passages extending through the body for discharging drilling fluid pumped down the drill string. Nozzles are located at the outlets of the passages. The nozzle is normally of tungsten carbide to resist erosion.
Drill bit nozzles have been retained in many different manners. In rolling cutter bits, the nozzles are normally retained by snap rings. In the PDC type bit, it is desirable to have easily replaceable nozzles. An easily replaceable nozzle allows the personnel in the field to change the size of the nozzles for different bit hydraulics, even after the bit has drilled on prior occasions. PDC bits are often used for drilling specified intervals and may be reused on different wells. Some ring retained nozzles cannot be replaced, because the ring is recessed to prevent erosion. Many PDC type bits use a separate steel threaded nut located below the nozzle for retaining the nozzle in the passage. In U.S. Pat. No. 4,381,825, Radtke, May 3, 1983, the nozzle has a steel sleeve brazed onto the tungsten carbide body of the nozzle to allow the nozzle to be secured by threads into the bit passage.